TBE focal areas normally exist in biotopes where Ixodes ricinus and its hosts find optimal living conditions. Infected ticks are frequently found on forest fringes with adjacent grassland, glades, riverside meadows and marsh-lands, forest plantations with brushwood and shrubbery, on the transition between deciduous and coniferous forests or between timber and coppic. Oak/hornbeam, as well as beech/fir woods with a rich undergrowth of weeds, ferns, elder, hazel, and bramble bushes, provide an ideal habitat for ticks. Sites of infestation are frequently situated on sunny slopes facing south and having a low plant cover of shrubs and hedges.
Such rural landscapes, especially when benches, cross-country tracks or barbecue pits are provided, attract many people so that an increased risk of infection must be expected. It has been shown in various studies that TBE natural foci are usually not eliminated by cultivation of the landscape. Exposure to ticks is also possible in newly created gardens or ticks are transported to homes by way of dogs, flowers, branches, or on clothing. Reducing the habitats of small mammals to a few areas not suitable for cultivation also leads to an increased circulation of TBE virus, because the probability of virus transmission rises with the population density of the hosts.
Contrary to a widespread belief, ticks do not sit on trees and jump down onto their hosts, but rather prefer vegetation that is closer to ground level. Larvae are usually found on grass up to a level of 30cm, nymphs on herbs and plants of less than 1m, and imagos on weeds or shrubs up to 1.5m high.
Keeping to the underside of foliage, ticks mostly sit at the ends of leaves or branches next to footpaths and the trails of wild animals, from where they drop onto their hosts or are brushed off by them.
In adult humans, ticks tend to attach themselves to the legs as well as the gluteal and genital regions. In children, 75% of tick bites are observed on the head, in the remaining cases legs and arms, trunk, gluteal and genital regions are affected.